<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>18 Q | Glossary</title>
<meta name="author" content="psyTeachR Team">
<meta name="description" content="18.1 Q-Q plot A scatterplot created by plotting two sets of quantiles against each other, used to check if data come from a specified distribution It is pretty difficult to tell from looking at a...">
<meta name="generator" content="bookdown 0.24 with bs4_book()">
<meta property="og:title" content="18 Q | Glossary">
<meta property="og:type" content="book">
<meta property="og:url" content="https://psyteachr.github.io/glossary/q.html">
<meta property="og:image" content="https://psyteachr.github.io/glossary/images/logos/logo.png">
<meta property="og:description" content="18.1 Q-Q plot A scatterplot created by plotting two sets of quantiles against each other, used to check if data come from a specified distribution It is pretty difficult to tell from looking at a...">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="18 Q | Glossary">
<meta name="twitter:description" content="18.1 Q-Q plot A scatterplot created by plotting two sets of quantiles against each other, used to check if data come from a specified distribution It is pretty difficult to tell from looking at a...">
<meta name="twitter:image" content="https://psyteachr.github.io/glossary/images/logos/logo.png">
<!-- JS --><script src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.6/clipboard.min.js" integrity="sha256-inc5kl9MA1hkeYUt+EC3BhlIgyp/2jDIyBLS6k3UxPI=" crossorigin="anonymous"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/fuse.js/6.4.6/fuse.js" integrity="sha512-zv6Ywkjyktsohkbp9bb45V6tEMoWhzFzXis+LrMehmJZZSys19Yxf1dopHx7WzIKxr5tK2dVcYmaCk2uqdjF4A==" crossorigin="anonymous"></script><script src="https://kit.fontawesome.com/6ecbd6c532.js" crossorigin="anonymous"></script><script src="libs/header-attrs-2.11/header-attrs.js"></script><script src="libs/jquery-3.6.0/jquery-3.6.0.min.js"></script><meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link href="libs/bootstrap-4.6.0/bootstrap.min.css" rel="stylesheet">
<script src="libs/bootstrap-4.6.0/bootstrap.bundle.min.js"></script><script src="libs/bs3compat-0.3.1/transition.js"></script><script src="libs/bs3compat-0.3.1/tabs.js"></script><script src="libs/bs3compat-0.3.1/bs3compat.js"></script><link href="libs/bs4_book-1.0.0/bs4_book.css" rel="stylesheet">
<script src="libs/bs4_book-1.0.0/bs4_book.js"></script><script src="libs/kePrint-0.0.1/kePrint.js"></script><link href="libs/lightable-0.0.1/lightable.css" rel="stylesheet">
<!-- Global site tag (gtag.js) - Google Analytics --><script async src="https://www.googletagmanager.com/gtag/js?id=G-6NP3MF25W3"></script><script>
      window.dataLayer = window.dataLayer || [];
      function gtag(){dataLayer.push(arguments);}
      gtag('js', new Date());

      gtag('config', 'G-6NP3MF25W3');
    </script><script src="https://cdnjs.cloudflare.com/ajax/libs/autocomplete.js/0.38.0/autocomplete.jquery.min.js" integrity="sha512-GU9ayf+66Xx2TmpxqJpliWbT5PiGYxpaG8rfnBEk1LL8l1KGkRShhngwdXK1UgqhAzWpZHSiYPc09/NwDQIGyg==" crossorigin="anonymous"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/mark.js/8.11.1/mark.min.js" integrity="sha512-5CYOlHXGh6QpOFA/TeTylKLWfB3ftPsde7AnmhuitiTX4K5SqCLBeKro6sPS8ilsz1Q4NRx3v8Ko2IBiszzdww==" crossorigin="anonymous"></script><!-- CSS --><link rel="stylesheet" href="include/psyteachr.css">
<link rel="stylesheet" href="include/webex.css">
<link rel="stylesheet" href="include/style.css">
</head>
<body data-spy="scroll" data-target="#toc">

<div class="container-fluid">
<div class="row">
  <header class="col-sm-12 col-lg-3 sidebar sidebar-book"><a class="sr-only sr-only-focusable" href="#content">Skip to main content</a>

    <div class="d-flex align-items-start justify-content-between">
      <h1>
        <a href="index.html" title="">Glossary</a>
      </h1>
      <button class="btn btn-outline-primary d-lg-none ml-2 mt-1" type="button" data-toggle="collapse" data-target="#main-nav" aria-expanded="true" aria-controls="main-nav"><i class="fas fa-bars"></i><span class="sr-only">Show table of contents</span></button>
    </div>

    <div id="main-nav" class="collapse-lg">
      <form role="search">
        <input id="search" class="form-control" type="search" placeholder="Search" aria-label="Search">
</form>

      <nav aria-label="Table of contents"><h2>Table of contents</h2>
        <ul class="book-toc list-unstyled">
<li><a class="" href="index.html">Overview</a></li>
<li><a class="" href="symbols.html"><span class="header-section-number">1</span> Symbols</a></li>
<li><a class="" href="a.html"><span class="header-section-number">2</span> A</a></li>
<li><a class="" href="b.html"><span class="header-section-number">3</span> B</a></li>
<li><a class="" href="c.html"><span class="header-section-number">4</span> C</a></li>
<li><a class="" href="d.html"><span class="header-section-number">5</span> D</a></li>
<li><a class="" href="e.html"><span class="header-section-number">6</span> E</a></li>
<li><a class="" href="f.html"><span class="header-section-number">7</span> F</a></li>
<li><a class="" href="g.html"><span class="header-section-number">8</span> G</a></li>
<li><a class="" href="h.html"><span class="header-section-number">9</span> H</a></li>
<li><a class="" href="i.html"><span class="header-section-number">10</span> I</a></li>
<li><a class="" href="j.html"><span class="header-section-number">11</span> J</a></li>
<li><a class="" href="k.html"><span class="header-section-number">12</span> K</a></li>
<li><a class="" href="l.html"><span class="header-section-number">13</span> L</a></li>
<li><a class="" href="m.html"><span class="header-section-number">14</span> M</a></li>
<li><a class="" href="n.html"><span class="header-section-number">15</span> N</a></li>
<li><a class="" href="o.html"><span class="header-section-number">16</span> O</a></li>
<li><a class="" href="p.html"><span class="header-section-number">17</span> P</a></li>
<li><a class="active" href="q.html"><span class="header-section-number">18</span> Q</a></li>
<li><a class="" href="r.html"><span class="header-section-number">19</span> R</a></li>
<li><a class="" href="s.html"><span class="header-section-number">20</span> S</a></li>
<li><a class="" href="t.html"><span class="header-section-number">21</span> T</a></li>
<li><a class="" href="u.html"><span class="header-section-number">22</span> U</a></li>
<li><a class="" href="v.html"><span class="header-section-number">23</span> V</a></li>
<li><a class="" href="w.html"><span class="header-section-number">24</span> W</a></li>
<li><a class="" href="x.html"><span class="header-section-number">25</span> X</a></li>
<li><a class="" href="y.html"><span class="header-section-number">26</span> Y</a></li>
<li><a class="" href="z.html"><span class="header-section-number">27</span> Z</a></li>
</ul>

        <div class="book-extra">
          <p><a id="book-repo" href="https://github.com/psyteachr/glossary">View book source <i class="fab fa-github"></i></a></p>
        </div>
      </nav>
</div>
  </header><main class="col-sm-12 col-md-9 col-lg-7" id="content"><div id="q" class="section level1" number="18">
<h1>
<span class="header-section-number">18</span> Q<a class="anchor" aria-label="anchor" href="#q"><i class="fas fa-link"></i></a>
</h1>

<div id="q-q-plot" class="section level2" number="18.1">
<h2>
<span class="header-section-number">18.1</span> Q-Q plot<a class="anchor" aria-label="anchor" href="#q-q-plot"><i class="fas fa-link"></i></a>
</h2>
<p><dfn>A scatterplot created by plotting two sets of <a href="q.html#quantile">quantiles</a> against each other, used to check if data come from a specified <a href="d.html#distribution">distribution</a></dfn></p>
<p>It is pretty difficult to tell from looking at a density plot if data are distributed in a specific way. We often want to determine if, for example, the residuals of a model are normally distributed. Q-Q plots can help with this.</p>
<p>Let's simulate 25 data points from a normal distribution with a mean of 100 and SD of 10. Since there are not many data points, the resulting plot will be pretty lumpy. The red line is a perfect normal distribution.</p>
<div class="sourceCode" id="cb171"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="va">A</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/stats/Normal.html">rnorm</a></span><span class="op">(</span><span class="fl">25</span>, <span class="fl">100</span>, <span class="fl">10</span><span class="op">)</span>

<span class="fu">ggplot</span><span class="op">(</span><span class="op">)</span> <span class="op">+</span> 
  <span class="fu">geom_density</span><span class="op">(</span><span class="fu">aes</span><span class="op">(</span><span class="va">A</span><span class="op">)</span><span class="op">)</span> <span class="op">+</span>
  <span class="fu">geom_function</span><span class="op">(</span>fun <span class="op">=</span> <span class="va">dnorm</span>, 
                args <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/list.html">list</a></span><span class="op">(</span>mean <span class="op">=</span> <span class="fl">100</span>, sd <span class="op">=</span> <span class="fl">10</span><span class="op">)</span>,
                colour <span class="op">=</span> <span class="st">"red"</span><span class="op">)</span></code></pre></div>
<div class="figure" style="text-align: center">
<span style="display:block;" id="fig:qq-density"></span>
<img src="_main_files/figure-html/qq-density-1.png" alt="Density plot of sample data and the normal distribution it was drawn from" width="100%"><p class="caption">
Figure 18.1: Density plot of sample data and the normal distribution it was drawn from
</p>
</div>
<p>A Q-Q plot calculates what <a href="q.html#quantile">quantile</a> each data point is in, and plots that against the theoretical quantiles from the normal distribution. The red line is the theoretically perfect noraml distribution, so you just need to assess if most of the points fall on this line.</p>
<div class="sourceCode" id="cb172"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="fu">qplot</span><span class="op">(</span>sample <span class="op">=</span> <span class="va">A</span><span class="op">)</span> <span class="op">+</span> <span class="fu">geom_qq_line</span><span class="op">(</span>colour <span class="op">=</span> <span class="st">"red"</span><span class="op">)</span></code></pre></div>
<div class="figure" style="text-align: center">
<span style="display:block;" id="fig:qq-A"></span>
<img src="_main_files/figure-html/qq-A-1.png" alt="Q-Q plot of a small sample from a normal distribution" width="100%"><p class="caption">
Figure 18.2: Q-Q plot of a small sample from a normal distribution
</p>
</div>
<p>Here's what it might look like if your data are actually from a uniform distribution.</p>
<div class="sourceCode" id="cb173"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="va">U</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/stats/Uniform.html">runif</a></span><span class="op">(</span><span class="fl">25</span>, <span class="fl">0</span>, <span class="fl">10</span><span class="op">)</span>
<span class="fu">qplot</span><span class="op">(</span>sample <span class="op">=</span> <span class="va">U</span><span class="op">)</span> <span class="op">+</span> <span class="fu">geom_qq_line</span><span class="op">(</span>colour <span class="op">=</span> <span class="st">"red"</span><span class="op">)</span></code></pre></div>
<div class="figure" style="text-align: center">
<span style="display:block;" id="fig:qq-unif"></span>
<img src="_main_files/figure-html/qq-unif-1.png" alt="Q-Q plot of a uniform distribution" width="100%"><p class="caption">
Figure 18.3: Q-Q plot of a uniform distribution
</p>
</div>

</div>
<div id="quantile" class="section level2" number="18.2">
<h2>
<span class="header-section-number">18.2</span> quantile<a class="anchor" aria-label="anchor" href="#quantile"><i class="fas fa-link"></i></a>
</h2>
<p><dfn>Cutoffs dividing the range of a <a href="#d.htmldistribution">distribution</a> into continuous intervals with equal probabilities.</dfn></p>
<p>You can take a sample of numbers on divide them into N equally-sized groups. Let's use these 12 numbers as an example:</p>
<div class="sourceCode" id="cb174"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="va">x</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/c.html">c</a></span><span class="op">(</span><span class="fl">1</span>, <span class="fl">1</span>, <span class="fl">2</span>, <span class="fl">2</span>, <span class="fl">3</span>, <span class="fl">4</span>, <span class="fl">4</span>, <span class="fl">5</span>, <span class="fl">7</span>, <span class="fl">7</span>, <span class="fl">7</span>, <span class="fl">10</span><span class="op">)</span></code></pre></div>
<p>The <code><a href="https://rdrr.io/r/stats/quantile.html">quantile()</a></code> function gives you the cutoffs for each quantile from the data. Set the argument <code>probs</code> to <code><a href="https://rdrr.io/r/base/seq.html">seq(0, 1, 1/N)</a></code> for any N-tile.</p>
<div class="sourceCode" id="cb175"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="co"># median</span>
<span class="fu"><a href="https://rdrr.io/r/stats/quantile.html">quantile</a></span><span class="op">(</span><span class="va">x</span>, probs <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/seq.html">seq</a></span><span class="op">(</span><span class="fl">0</span>, <span class="fl">1</span>, <span class="fl">1</span><span class="op">/</span><span class="fl">2</span><span class="op">)</span><span class="op">)</span>
<span class="co">#&gt;   0%  50% 100% </span>
<span class="co">#&gt;    1    4   10</span></code></pre></div>
<div class="sourceCode" id="cb176"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="co"># tertile</span>
<span class="fu"><a href="https://rdrr.io/r/stats/quantile.html">quantile</a></span><span class="op">(</span><span class="va">x</span>, probs <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/seq.html">seq</a></span><span class="op">(</span><span class="fl">0</span>, <span class="fl">1</span>, <span class="fl">1</span><span class="op">/</span><span class="fl">3</span><span class="op">)</span><span class="op">)</span>
<span class="co">#&gt;        0% 33.33333% 66.66667%      100% </span>
<span class="co">#&gt;  1.000000  2.666667  5.666667 10.000000</span></code></pre></div>
<div class="sourceCode" id="cb177"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="co"># quartile</span>
<span class="fu"><a href="https://rdrr.io/r/stats/quantile.html">quantile</a></span><span class="op">(</span><span class="va">x</span>, probs <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/seq.html">seq</a></span><span class="op">(</span><span class="fl">0</span>, <span class="fl">1</span>, <span class="fl">1</span><span class="op">/</span><span class="fl">4</span><span class="op">)</span><span class="op">)</span>
<span class="co">#&gt;   0%  25%  50%  75% 100% </span>
<span class="co">#&gt;    1    2    4    7   10</span></code></pre></div>
<div class="sourceCode" id="cb178"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="va">dat</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/data.frame.html">data.frame</a></span><span class="op">(</span>
  x <span class="op">=</span> <span class="va">x</span>
<span class="op">)</span> <span class="op">%&gt;%</span>
  <span class="fu"><a href="https://dplyr.tidyverse.org/reference/mutate.html">mutate</a></span><span class="op">(</span>
  `2-tile` <span class="op">=</span> <span class="fu"><a href="https://dplyr.tidyverse.org/reference/ranking.html">ntile</a></span><span class="op">(</span><span class="va">x</span>, <span class="fl">2</span><span class="op">)</span>,
  `3-tile` <span class="op">=</span> <span class="fu"><a href="https://dplyr.tidyverse.org/reference/ranking.html">ntile</a></span><span class="op">(</span><span class="va">x</span>, <span class="fl">3</span><span class="op">)</span>,
  `4-tile` <span class="op">=</span> <span class="fu"><a href="https://dplyr.tidyverse.org/reference/ranking.html">ntile</a></span><span class="op">(</span><span class="va">x</span>, <span class="fl">4</span><span class="op">)</span>,
  `6-tile` <span class="op">=</span> <span class="fu"><a href="https://dplyr.tidyverse.org/reference/ranking.html">ntile</a></span><span class="op">(</span><span class="va">x</span>, <span class="fl">6</span><span class="op">)</span>
<span class="op">)</span></code></pre></div>
<div class="inline-table"><table class="table table-sm">
<thead><tr>
<th style="text-align:right;">
x
</th>
<th style="text-align:right;">
2-tile
</th>
<th style="text-align:right;">
3-tile
</th>
<th style="text-align:right;">
4-tile
</th>
<th style="text-align:right;">
6-tile
</th>
</tr></thead>
<tbody>
<tr>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
</tr>
<tr>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
</tr>
<tr>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
2
</td>
</tr>
<tr>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
2
</td>
</tr>
<tr>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
</tr>
<tr>
<td style="text-align:right;">
4
</td>
<td style="text-align:right;">
1
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
</tr>
<tr>
<td style="text-align:right;">
4
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
4
</td>
</tr>
<tr>
<td style="text-align:right;">
5
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
4
</td>
</tr>
<tr>
<td style="text-align:right;">
7
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
5
</td>
</tr>
<tr>
<td style="text-align:right;">
7
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
4
</td>
<td style="text-align:right;">
5
</td>
</tr>
<tr>
<td style="text-align:right;">
7
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
4
</td>
<td style="text-align:right;">
6
</td>
</tr>
<tr>
<td style="text-align:right;">
10
</td>
<td style="text-align:right;">
2
</td>
<td style="text-align:right;">
3
</td>
<td style="text-align:right;">
4
</td>
<td style="text-align:right;">
6
</td>
</tr>
</tbody>
</table></div>
<p>See <a href="q.html#q-q-plots">Q_Q plots</a>.</p>

</div>
</div>
<script>

/* update total correct if #webex-total_correct exists */
update_total_correct = function() {
  console.log("webex: update total_correct");

  if (t = document.getElementById("webex-total_correct")) {
    var correct = document.getElementsByClassName("webex-correct").length;
    var solvemes = document.getElementsByClassName("webex-solveme").length;
    var radiogroups = document.getElementsByClassName("webex-radiogroup").length;
    var selects = document.getElementsByClassName("webex-select").length;
    
    t.innerHTML = correct + " of " + (solvemes + radiogroups + selects) + " correct";
  }
}

/* webex-solution button toggling function */
b_func = function() {
  console.log("webex: toggle hide");
  
  var cl = this.parentElement.classList;
  if (cl.contains('open')) {
    cl.remove("open");
  } else {
    cl.add("open");
  }
}

/* function for checking solveme answers */
solveme_func = function(e) {
  console.log("webex: check solveme");

  var real_answers = JSON.parse(this.dataset.answer);
  var my_answer = this.value;
  var cl = this.classList;
  if (cl.contains("ignorecase")) {
    my_answer = my_answer.toLowerCase();
  }
  if (cl.contains("nospaces")) {
    my_answer = my_answer.replace(/ /g, "")
  }

  if (my_answer == "") {
    cl.remove("webex-correct");
    cl.remove("webex-incorrect");
  } else if (real_answers.includes(my_answer)) {
    cl.add("webex-correct");
    cl.remove("webex-incorrect");
  } else {
    cl.add("webex-incorrect");
    cl.remove("webex-correct");
  }

  // match numeric answers within a specified tolerance
  if(this.dataset.tol > 0){
    var tol = JSON.parse(this.dataset.tol);
    var matches = real_answers.map(x => Math.abs(x - my_answer) < tol)
    if (matches.reduce((a, b) => a + b, 0) > 0) {
      cl.add("webex-correct");
    } else {
      cl.remove("webex-correct");
    }
  }

  // added regex bit
  if (cl.contains("regex")){
    answer_regex = RegExp(real_answers.join("|"))
    if (answer_regex.test(my_answer)) {
      cl.add("webex-correct");
    }
  }

  update_total_correct();
}

/* function for checking select answers */
select_func = function(e) {
  console.log("webex: check select");
  
  var cl = this.classList
  
  /* add style */
  cl.remove("webex-incorrect");
  cl.remove("webex-correct");
  if (this.value == "answer") {
    cl.add("webex-correct");
  } else if (this.value != "blank") {
    cl.add("webex-incorrect");
  }
  
  update_total_correct();
}

/* function for checking radiogroups answers */
radiogroups_func = function(e) {
  console.log("webex: check radiogroups");

  var checked_button = document.querySelector('input[name=' + this.id + ']:checked');
  var cl = checked_button.parentElement.classList;
  var labels = checked_button.parentElement.parentElement.children;
  
  /* get rid of styles */
  for (i = 0; i < labels.length; i++) {
    labels[i].classList.remove("webex-incorrect");
    labels[i].classList.remove("webex-correct");
  }
  
  /* add style */
  if (checked_button.value == "answer") {
    cl.add("webex-correct");
  } else {
    cl.add("webex-incorrect");
  }
  
  update_total_correct();
}

window.onload = function() {
  console.log("onload");
  /* set up solution buttons */
  var buttons = document.getElementsByTagName("button");

  for (var i = 0; i < buttons.length; i++) {
    if (buttons[i].parentElement.classList.contains('webex-solution')) {
      buttons[i].onclick = b_func;
    }
  }

  /* set up webex-solveme inputs */
  var solveme = document.getElementsByClassName("webex-solveme");

  for (var i = 0; i < solveme.length; i++) {
    /* make sure input boxes don't auto-anything */
    solveme[i].setAttribute("autocomplete","off");
    solveme[i].setAttribute("autocorrect", "off");
    solveme[i].setAttribute("autocapitalize", "off");
    solveme[i].setAttribute("spellcheck", "false");
    solveme[i].value = "";

    /* adjust answer for ignorecase or nospaces */
    var cl = solveme[i].classList;
    var real_answer = solveme[i].dataset.answer;
    if (cl.contains("ignorecase")) {
      real_answer = real_answer.toLowerCase();
    }
    if (cl.contains("nospaces")) {
      real_answer = real_answer.replace(/ /g, "");
    }
    solveme[i].dataset.answer = real_answer;

    /* attach checking function */
    solveme[i].onkeyup = solveme_func;
    solveme[i].onchange = solveme_func;
  }
  
  /* set up radiogroups */
  var radiogroups = document.getElementsByClassName("webex-radiogroup");
  for (var i = 0; i < radiogroups.length; i++) {
    radiogroups[i].onchange = radiogroups_func;
  }
  
  /* set up selects */
  var selects = document.getElementsByClassName("webex-select");
  for (var i = 0; i < selects.length; i++) {
    selects[i].onchange = select_func;
  }

  update_total_correct();
}

</script><script>
$( document ).ready(function() {
  var cite = ' ';
  var psyteachr = ' <a href="https://psyteachr.github.io/"><img src="images/logos/psyteachr_logo.png" style="height: 31px; color: white;" alt="psyTeachR: Reproducible Research" /></a>';
  var license = ' <a rel="license" href="https://creativecommons.org/licenses/by-sa/4.0/" target="blank"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png"></a>';

  $("footer div.row div:eq(1) p").html(
    psyteachr + license + cite
  );
  
  $("#toc").appendTo($("#main-nav"));
});
</script><div class="chapter-nav">
<div class="prev"><a href="p.html"><span class="header-section-number">17</span> P</a></div>
<div class="next"><a href="r.html"><span class="header-section-number">19</span> R</a></div>
</div></main><div class="col-md-3 col-lg-2 d-none d-md-block sidebar sidebar-chapter">
    <nav id="toc" data-toggle="toc" aria-label="On this page"><h2>On this page</h2>
      <ul class="nav navbar-nav">
<li><a class="nav-link" href="#q"><span class="header-section-number">18</span> Q</a></li>
<li><a class="nav-link" href="#q-q-plot"><span class="header-section-number">18.1</span> Q-Q plot</a></li>
<li><a class="nav-link" href="#quantile"><span class="header-section-number">18.2</span> quantile</a></li>
</ul>

      <div class="book-extra">
        <ul class="list-unstyled">
<li><a id="book-source" href="https://github.com/psyteachr/glossary/blob/master/terms/q-.Rmd">View source <i class="fab fa-github"></i></a></li>
          <li><a id="book-edit" href="https://github.com/psyteachr/glossary/edit/master/terms/q-.Rmd">Edit this page <i class="fab fa-github"></i></a></li>
        </ul>
</div>
    </nav>
</div>

</div>
</div> <!-- .container -->

<footer class="bg-primary text-light mt-5"><div class="container"><div class="row">

  <div class="col-12 col-md-6 mt-3">
    <p>"<strong>Glossary</strong>" was written by psyTeachR Team. It was last built on 2022-02-10.</p>
  </div>

  <div class="col-12 col-md-6 mt-3">
    <p>This book was built by the <a class="text-light" href="https://bookdown.org">bookdown</a> R package.</p>
  </div>

</div></div>
</footer><!-- dynamically load mathjax for compatibility with self-contained --><script>
  (function () {
    var script = document.createElement("script");
    script.type = "text/javascript";
    var src = "true";
    if (src === "" || src === "true") src = "https://mathjax.rstudio.com/latest/MathJax.js?config=TeX-MML-AM_CHTML";
    if (location.protocol !== "file:")
      if (/^https?:/.test(src))
        src = src.replace(/^https?:/, '');
    script.src = src;
    document.getElementsByTagName("head")[0].appendChild(script);
  })();
</script><script type="text/x-mathjax-config">const popovers = document.querySelectorAll('a.footnote-ref[data-toggle="popover"]');
for (let popover of popovers) {
  const div = document.createElement('div');
  div.setAttribute('style', 'position: absolute; top: 0, left:0; width:0, height:0, overflow: hidden; visibility: hidden;');
  div.innerHTML = popover.getAttribute('data-content');

  var has_math = div.querySelector("span.math");
  if (has_math) {
    document.body.appendChild(div);
    MathJax.Hub.Queue(["Typeset", MathJax.Hub, div]);
    MathJax.Hub.Queue(function() {
      popover.setAttribute('data-content', div.innerHTML);
      document.body.removeChild(div);
    })
  }
}
</script>
</body>
</html>
